In conventional heating apparatus utilizing both dielectric heating and radiant energy heating, the microwave source and control circuit components therefor have generally been disposed beneath the heating chamber so that said source and components will not be exposed to the intense heat of the heating chamber. Particularly, in order that the heating chamber may be selfcleaned, the internal temperature of the chamber must be increased to about 500.degree. C. and this factor has precluded the positioning of the microwave source above the heating chamber. To avoid structural complexity, the control panel also has to be located low on the front wall of the body of the apparatus, so that it is not easy to manipulate.